This application is a National Phase Entry of PCT/IL01/00220 filed Mar. 8, 2001, which claims priority from Israel Patent Application Serial No. 134946 filed Mar. 8, 2000.
The present invention relates to electrical heating apparatus, and particularly to such apparatus for automatically heating water passing through the apparatus from a cold water supply pipe to a hot water delivery pipe.
Electrical heating apparatus of the foregoing type is widely used for providing instantaneous hot water from a cold water supply, such as for preparing a hot beverage, taking a hot shower, washing dishes, etc. Such apparatus generally includes a housing having an electrical heater, one or more electrical switches controlling the electrical heater, an inlet conduit connectable between the water supply pipe and the electrical heater for inletting cold water to the electrical heater, a pressure-responsive device cooperable with the electrical switches to control the electrical heater, a heater coupling for inletting the water into the electrical heater, and an outlet conduit connectable between the electrical heater and the water delivery pipe for outletting hot water from the electrical heater to the hot water delivery pipe. Some devices further include a control valve for controlling the water flow into the electrical heater. Generally, some or all of the foregoing components at the inlet side of the electrical heater are manufactured as separate units and assembled into the electrical heating apparatus at the time of its installation.
Producing the foregoing components as separate units increases the time and cost of installing such an electrical heating apparatus, as well as the time for disassembling the apparatus for purposes of maintenance and/or repair.
An object of the present invention is to provide electrical heating apparatus which enables faster installation, as well as more convenient maintenance and repair, of the apparatus.
According to one aspect of the present invention, there is provided electrical heating apparatus for automatically heating water passing therethrough from a cold water supply pipe to a hot water delivery pipe, comprising: a water heater housing including an electrical heater therein, an inlet coupling, and an outlet coupling; an electrical control device controlling said electrical heater; an inlet conduit connectable between the water supply pipe and the inlet coupling of the electrical heater housing for inletting cold water; an outlet conduit connectable between the outlet coupling of the water heater housing and the water delivery pipe for outletting hot water thereto; and a pressure-responsive device cooperable with said electrical control device to control the electrical heater; characterized in that said pressure-responsive device is connected to one of said conduits in parallel to said electrical heater housing, and in that said pressure-responsive device includes an inlet integrally formed with said one conduit and the respective coupling of water heater housing.
Preferably, the conduit integrally formed with the pressure-responsive device inlet is the inlet conduit connectable between the water supply pipe and the inlet coupling of the electrical heater housing. Also preferably, the inlet conduit is also integrally formed with the inlet coupling.
Such a construction greatly facilitates installation, maintenance and repair of the apparatus.
A number of embodiments of the invention are described below for purposes of example.
In some of the described embodiments, the apparatus further comprises a control valve for controlling the water flow into the electrical heater; the control valve including a housing having an inlet also integrally formed with the inlet conduit and with at least part of the control valve housing, thereby further facilitating installation, maintenance and repair of the apparatus. Several embodiments are described below in which the control valve is a manually presettable valve, particularly a ball valve having a ball rotatable within the control valve housing and formed with a variable-depth passageway for controlling the water flow therethrough to the electrical heater. In other described embodiments, the control valve is a regulator valve automatically regulating the water flow therethrough to have a relatively constant rate despite variations in the water inlet pressure.
However, embodiments are also described below wherein no control valve is provided within the electrical heating apparatus itself in which case, the water flow would be controlled by a separate valve upstream of the electrical heating apparatus.
In some of the embodiments of the invention described below, the pressure-responsive device senses the pressure at the inlet to the device to control the energization of the electrical heater; in these embodiments, the electrical heater is normally deenergized, but is automatically energized as soon as the inlet pressure is applied. Such an electrical heater would also be provided with a thermostat control to turn-off the electrical heater when the water therein reaches a predetermined temperature, which can occur quite rapidly if there is no water flow through the electrical heater.
Other embodiments of the invention are described below wherein the pressure-responsive device senses the flow rate through it to control the energization of the electrical heater. In the described preferred embodiments, the pressure-responsive device senses the flow rate by sensing the difference in pressure at the inlet and outlet of the pressure-responsive device. Thus, if the pressure difference is substantially zero, this indicates that there is no flow through that device, and therefore it will not energize the electrical heater; whereas if the pressure difference is significant, this will indicate flow through the device, and therefore the device will energize the electrical heater.
According to further features in further embodiments described below, the pressure-responsive device includes a displaceable member which is displaceable according to the sensed differential pressure and operates the electrical control device, preferably a plurality of electrical switches, to control the electrical heater in accordance with the displacement of the displaceable member. According to one embodiment, the displaceable member actuates all the switches simultaneously; and in other embodiments, it sequentially actuates the electrical switches according to the magnitude of the displacement of that member. This controls the magnitude of the electrical heat produced by the electrical heater according to the water flow rate, so that high heat will be produced at high water flow rates, and lower heat will be produced at lower flow rates.
According to another aspect of the present invention, there is provided electrical heating apparatus for automatically heating water passing therethrough from a cold water supply pipe to a hot water delivery pipe, comprising: a housing including an electrical heater therein; an electrical control device controlling the electrical heater; an inlet conduit connectable between the water supply pipe and the electrical heater for inletting cold water to the electrical heater; a heater coupling communicating with the inlet conduit for inletting water therefrom into the electrical heater; an outlet conduit connectable between the electrical heater and the water delivery pipe for outletting hot water thereto from the electrical heater; and a pressure-responsive device cooperable with the electrical control device to control the electrical heater and having an inlet communicating with the inlet conduit and heater coupling; characterized in that the pressure-responsive device senses the flow rate to or through the electrical heater to control the energization of the electrical heater in response to the sensed flow rate.
According to a still further aspect of the present invention, there is provided a regulating valve comprising a housing; a membrane within the housing; and a stem within the housing having a head of convex configuration facing the membrane but normally spaced therefrom to define a flow-control passageway; the convex configuration of the stem head producing, with the membrane, different cross-sectional areas and thereby different flow rates in the control passageway, creating differential pressures acting on the membrane tending to deform the membrane such as to maintain a relatively constant flow rate through the flow control passageway despite variations in water inlet pressure.
Further features and advantages of the invention will be apparent from the description below.